Before a key Thursday Senate vote on a trade bill, Florida Republican Sen. Marco Rubio filed an amendment to restrict worker aid provided to people adversely affected by foreign competition.

A program called Trade Adjustment Assistance, begun during the Kennedy administration, provides money and retraining to workers hurt by trade. When Congress passed the federal stimulus package in 2009, it expanded the program, removing a requirement that the workers it assists were affected by a free-trade agreement -- just by trade in general.

That free-trade agreement requirement should be put back in place, Rubio argued.

"This program is originally designed to help workers who were harmed in the short term," he said on the Senate floor. "That's why it's called 'adjustment.'"

The best thing to do for an unemployed worker, he added, is to find him a new job. "And that's what free trade agreements can do," Rubio said.

The Senate is trying to strike a delicate balance by sticking the worker aid changes in the trade bill: Republicans generally don't like expansion of the aid, but want Congress to move forward on trade agreements with Colombia, Panama and South Korea. Democrats, who have stalled the trade agreements, like the worker aid, and have signaled they could take up the agreements if the expanded aid continues. (Colombians in particular have become an increasingly important South Florida constituency.)

President Barack Obama has started to push for the agreements as part of his plan to create jobs.